The present disclosure relates generally to methods for forming tribological thin films, and more specifically to a sol-gel route for forming durable, scratch-resistant coatings on glass substrates.
Scratches and other types of surface wear are a concern for glass cover applications such as in hand held devices, monitors and displays. Scratches increase the scattering of light and can reduce the brightness and contrast of images and text that is presented on such screens. Further, in the device-off state, scratches can make the display look hazy, marred and unattractive. In particular for displays and handheld devices, scratch resistance can be an important attribute.
In particular, the formation of microductile scratches can be attenuated by adjusting the hardness of the surface that is being scratched. Microductile scratches shallow or narrow scratches characterized by a scratch depth or scratch width of less than 2 microns. Harder surfaces typically are more resistant to microductile scratching. While oxide glasses that form the glass substrates used in many glass covers typically have hardness values in the range of 6 to 9 GPa, the propensity of microductile scratch formation can be dramatically decreased by forming a hard, lubricious surface layer on the glass where the surface layer has a hardness value greater than 9 GPa.
It would be desirable to provide scratch-resistant coatings that can be applied to rigid glass covers that are economical, optically transparent and physically and chemically compatible with the underlying glass.